Revert "Fix bad type-inferrence for logical expressions."

sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart

Index: sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
diff --git a/sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart b/sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
index 743a24fa20bed3cad5c6806497e2bc69ac5bb164..86662f7dcb798a5ba86b62cd839375bd13f04499 100644
--- a/sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
+++ b/sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.dart
@@ -835,18 +835,6 @@ abstract class InferrerVisitor
     }
   }
 
-  /// Stops the accumulation of is-checks.
-  ///
-  /// Nulls the [isChecks] field.
-  ///
-  /// Returns the old value of [accumulateIsChecks].
-  bool stopAccumulatingIsChecks() {
-    bool oldAccumulateIsChecks = accumulateIsChecks;
-    accumulateIsChecks = false;
-    isChecks = null;
-    return oldAccumulateIsChecks;
-  }
-
   T visitOperatorSend(Send node) {
     Operator op = node.selector;
     if ("[]" == op.source) {
@@ -854,15 +842,11 @@ abstract class InferrerVisitor
     } else if ("&&" == op.source) {
       conditionIsSimple = false;
       bool oldAccumulateIsChecks = accumulateIsChecks;
-      if (!accumulateIsChecks) {
-        accumulateIsChecks = true;
-        isChecks = <Send>[];
-      }
+      accumulateIsChecks = true;
+      if (isChecks == null) isChecks = <Send>[];
       visit(node.receiver);
-      if (!oldAccumulateIsChecks) {
-        accumulateIsChecks = false;
-        isChecks = null;
-      }
+      accumulateIsChecks = oldAccumulateIsChecks;
+      if (!accumulateIsChecks) isChecks = null;
       LocalsHandler<T> saved = locals;
       locals = new LocalsHandler<T>.from(locals, node);
       updateIsChecks(isChecks, usePositive: true);
@@ -873,18 +857,20 @@ abstract class InferrerVisitor
     } else if ("||" == op.source) {
       conditionIsSimple = false;
       List<Send> tests = <Send>[];
-      bool isSimple = handleCondition(node.receiver, tests);
+      handleCondition(node.receiver, tests);
       LocalsHandler<T> saved = locals;
       locals = new LocalsHandler<T>.from(locals, node);
-      if (isSimple) updateIsChecks(tests, usePositive: false);
-      bool oldAccumulateIsChecks = stopAccumulatingIsChecks();
+      updateIsChecks(tests, usePositive: false);
+      bool oldAccumulateIsChecks = accumulateIsChecks;
+      accumulateIsChecks = false;
       visit(node.arguments.head);
       accumulateIsChecks = oldAccumulateIsChecks;
       saved.mergeDiamondFlow(locals, null);
       locals = saved;
       return types.boolType;
     } else if ("!" == op.source) {
-      bool oldAccumulateIsChecks = stopAccumulatingIsChecks();
+      bool oldAccumulateIsChecks = accumulateIsChecks;
+      accumulateIsChecks = false;
       node.visitChildren(this);
       accumulateIsChecks = oldAccumulateIsChecks;
       return types.boolType;